This invention relates to the field of vibration damping and isolation. In particular, the present invention is a passive viscous damping and isolation system with active enhancement.
Precision structural systems carrying a load, such as a telescope system, are susceptible to disturbances that produce structural vibrations. Such vibrations may be contributed to the system by components or assemblies of the structural systems themselves, for example, reaction wheel assemblies used to point the telescope system. Since such precision structures tend to have little inherent damping, these vibrations can lead to serious performance degradation. Therefore, an efficient means of damping and isolating the load carried by the precision structures in a controlled manner is of considerable importance.
Both active damping isolation systems and passive damping isolation systems have been utilized. The limitations of passive damping isolation systems are well known. In particular, while passive isolators provide exceptional isolation at high frequency (above .sqroot.2 times resonant frequency), passive isolators amplify disturbances at low frequency. This deficiency in passive isolators is due primarily to the static stiffness requirements of flexure components of the passive isolators. In addition, in passive isolators the frequency dependence of the vibration damping is not easily tailored, since tailoring the damping typically requires changing the stiffness elements and/or the damping fluid. Changing of the damping fluid is a time consuming process which usually can only be performed properly in a factory setting. Active damping isolation systems, on the other hand, do provide desirable vibration damping at low frequency, and the frequency dependence of the vibration damping and isolation transmissibility of active isolators can be easily tailored. However, active isolators are typically more complex, and are higher in weight than comparable passive isolators. In addition, active isolators require power for operation, and as such, become inoperable upon a power failure. Hence, making active isolators unattractive from a reliability standpoint.
There is a need for improved damping isolation systems. In particular, there is a need for a damping isolation system that provides desirable vibration damping at high and low frequencies. In addition, the damping isolation system should provide easy tailoring of the frequency dependence of the vibration damping. The damping isolation system should provide these features while maintaining a weight efficient structure.